Laser deposition of elements onto medical devices

ABSTRACT

Devices and methods for fabricating medical devices are disclosed. A device in accordance with the present inventions includes a laser beam source capable of producing a laser beam, a carrier coupled to a carrier motion actuator capable of moving the carrier relative to the laser beam, and a workpiece motion actuator capable of moving a workpiece relative the laser beam. A method in accordance with the present invention includes the steps of positioning the carrier between the laser beam source and the workpiece, illuminating a portion of the carrier with the laser beam, moving the carrier relative to the laser beam, and moving the workpiece relative to the laser beam.

FIELD OF THE INVENTION

The present invention relates generally to medical devices andassociated methods of manufacture. More particularly, the presentinvention relates to the application of layers of material to thesurface of medical devices.

BACKGROUND OF THE INVENTION

In recent years there has been a great deal of interest in thedevelopment of devices which enable physicians to perform medicalprocedures in a way which is minimally invasive to the body of thepatient. These devices have been utilized to access many sites in thehuman body. Examples include coronary vasculature, cerebral vasculature,peripheral vasculature, and the gastrointestinal tract. During thefabrication of these devices, it is frequently necessary to apply anoverlaying material to the outer surface of a radial cylindrical device.Many examples of the need to apply overlaying materials to generallycylindrical medical devices may be found in devices which are utilizedto assure that the heart is properly perfused with blood.

Assuring that the heart muscle is adequately supplied with oxygen iscritical to sustaining the life of a patient. To receive an adequatesupply of oxygen, the heart muscle must be well perfused with blood. Ina healthy heart, blood perfusion is accomplished with a system of bloodvessels and capillaries. However, it is common for the blood vessels tobecome occluded (blocked) or stenotic (narrowed). A stenosis may beformed by an atheroma which is typically a harder, calcified substancewhich forms on the walls of a blood vessel. Individual stenotic lesionsmay be treated with a number of minimally invasive medical proceduresincluding angioplasty and atherectomy.

Angioplasty techniques typically involve the use of a balloon catheterand a guide catheter. During this procedure, the distal end of the guidecatheter is typically inserted into the femoral artery located near thegroin of the patient. The guide catheter is urged through thevasculature of the patient until its distal end is proximate therestriction. In many cases, the distal end of the guide catheter ispositioned in the ostium of the coronary artery.

In order to determine the location of the distal tip of the catheter, aring of radiopaque material may be disposed proximate the distal tip ofthe guide catheter. This ring of radiopaque material produces arelatively bright signal on a fluoroscopy screen, allowing the physicianto “see”where the tip of the catheter is located relative to thepatients anatomy. Radiopaque markers are one example of an element whichmay be fabricated by applying an overlaying material to a generallycylindrical medical device.

Once the guide catheter has been properly positioned, the ballooncatheter may be fed through a lumen in the guide catheter. The balloonis advanced beyond the distal end of the guide catheter until it ispositioned proximate a restriction in a diseased vessel. The balloon isthen inflated and the restriction in the vessel is opened. The ballooncatheter may also include a radiopaque ring to aid the physician inpositioning the balloon proximate the restriction.

Because a wide range of sizes and styles of catheters are used inangioplasty procedures it is desirable that the different sizes bereadily identifiable. Identifying marks may be placed on a catheter byapplying a layer of marking material. The marking material may definealphabetic or numeric characters. Alternately, the color or shape of thematerial may be used as an identifier. Visual identifiers are anadditional example of an element which may be fabricated by applying anoverlaying material to a generally cylindrical medical device.

To prevent subsequent closure of the vessel in the restricted area(restenosis) after an angioplasty procedure, a physician may implant astent. Stents are normally comprised of a generally cylindrical skeletalframe which includes openings and a lumen which extends longitudinallythrough the stent. A variety of processes are known for fabricatingstents. A stent may consist of a plurality of filaments or fibers whichare wound or braided together to form a continuous structure.Alternately, the skeletal frame of a stent may be formed by removingmaterial from a tubular element using a laser cutting process. Twogeneral types of stents are commonly used; self-expanding and balloonexpandable. A stent may be comprised of any biocompatible materialpossessing the structural and mechanical attributes necessary forsupporting a diseased vessel.

A stent may also include one or more layers of additional materialoverlying the skeletal frame. Examples of such materials include a drugrelease coating comprising a therapeutic substance in a polymericcarrier. Drug release coatings are an additional example of an elementwhich may be fabricated by applying an overlaying material to agenerally cylindrical medical device.

As mentioned above, individual stenotic lesions may also be treated withan atherectomy procedure. During an atherectomy procedure, a stenoticlesion is mechanically cut or abraded away from the blood vessel wall. Acatheter used in an atherectomy procedure may include an ablating burrhaving an abrasive coating. This abrasive coating may be fabricated byapplying a layer of material to a body member of the ablating burr. Thisabrasive material is an additional example of an element which may befabricate by applying an overlaying material to a generally cylindricalmedical device.

Percutaneous myocardial revascularization (PMR) is an additionalprocedure which may be performed to improve perfusion of the heartmuscle. PMR is typically used in clinical situations where angioplastyand atherectomy may not achieve the desired results. As described above,angioplasty, and atherectomy procedures have both been found effectivein treating individual stenotic lesions in relatively large bloodvessels. However, the heart muscle is perfused with blood through anetwork of small vessels and capillaries. In some cases, a large numberof stenotic lesions may occur in a large number of locations throughoutthis network of small blood vessels and capillaries. The torturous pathand small diameter of these blood vessels limit access to the stenoticlesions. The sheer number and small size of these stenotic lesions maketechniques such as angioplasty, and atherectomy impractical for somepatients.

When techniques which treat individual lesions are not practical, atechnique known as percutaneous myocardial revascularization (PMR) maybe used to improve the oxygenation of the myocardial tissue. A PMRprocedure generally involves the creation of holes, craters or channelsdirectly into the myocardium of the heart. PMR was inspired in part byobservations that reptilian heart muscles are supplied with oxygenprimarily by blood perfusing directly from within heart chambers to theheart muscle. This contrasts with the human heart, which is supplied bycoronary vessels receiving blood from the aorta. Positive clinicalresults have been demonstrated in human patients receiving PMRtreatments. These results are believed to be caused in part by bloodflowing within a heart chamber through channels in myocardial tissueformed by PMR. Increased blood flow to the myocardium is also believedto be caused in part by the healing response to wound formation.Specifically, the formation of new blood vessels is believed to occur inresponse to the newly created wound. This response is sometimes referredto as angiogenisis. In addition to promoting increased blood flow, it isalso believed that PMR improves a patient's condition throughdenervation. Denervation is the elimination of nerves. The creation ofwounds during a PMR procedure results in the elimination of nerveendings which were previously sending pain signals to the brain as aresult of hibernating tissue.

In a PMR procedure, hibernating heart tissue may be ablated using radiofrequency energy. In this procedure radio frequency energy is deliveredto the hibernating heart tissue using a catheter which includes one ormore conductors, and one or more electrodes. These conductors andelectrodes may be fabricated by applying one or more layers to the outersurface of a generally tubular member. For example, a conductivematerial such as gold may be applied to the generally tubular member tocreate electrodes, conductors, and or antennas. These electricallyconductive elements are an additional example of an element which may befabricated by applying an overlaying material to a generally cylindricalmedical device. Yet another example of elements which may be fabricatedby applying an overlaying material to a generally cylindrical medicaldevice include elements adapted to provide desirable structuralcharacteristics, for example, strain relief's, walls of varyingstiffness, etc.

SUMMARY OF INVENTION

The present invention relates generally to medical devices andassociated methods of manufacture. More particularly, the presentinvention relates to the application of layers of material to thesurface of medical devices. A system is disclosed which is capable ofdepositing material onto a workpiece.

In a presently preferred embodiment, the workpiece is a medical devicehaving a generally cylindrical surface. Also, in a presently preferredmethod, the workpiece is coupled to a workpiece motion control systemwhich is capable of moving workpiece. The workpiece motion controlsystem may include one or more linear actuators and one or more rotaryactuators.

A carrier is positioned in close proximity to the workpiece. The carrieris coupled to a carrier motion control system, which may include one ormore linear actuators and one or more rotary actuators. Severalembodiments of the carrier and the carrier motion control system aredisclosed. In a presently preferred embodiment, the carrier comprises asubstantially laser transparent substrate having a layer of writingmaterial overlaying at least a portion of one surface. Also in apresently preferred embodiment, the writing material comprises asacrificial layer and a projectile layer.

The system further includes a laser source which is capable of directinga laser beam. In a presently preferred embodiment, the laser source isstationary. In other possible embodiments, the laser source may becoupled to a laser motion control system which may include a pluralityof linear actuators and a plurality of rotary actuators. The actuatorsof the laser motion control system may be used to position the lasersource so that the laser beam eliminates a portion of the carrier. Asystem controller may be utilized to selectively activate and coordinatethe laser source, the laser motion control system, the carrier motioncontrol system, and the workpiece motion control system.

A catheter in accordance with the present invention may include a strainrelief or a radiopaque marker disposed on one of its surfaces utilizinga method in accordance with the present invention. Other elements whichmay be deposited on the surface of a workpiece utilizing methods inaccordance with the present invention include: visual markers,conductors, electrodes, and abrasive layers.

A method of applying material to a work surface in accordance with thepresent invention may begin with the step of coupling the workpiece tothe workpiece motion system. The carrier may likewise be coupled to thecarrier motion control system. The carrier may be positioned so that itis in close proximity to a surface of the workpiece. The laser motioncontrol system may be used to position the laser source such that thelaser beam illuminates a portion of the carrier and carrier isinterposed between laser source and workpiece.

The system controller may be utilized to selectively activate the lasersource, the laser motion control, the carrier motion control system, andthe workpiece motion control system. Relative motion is selectivelycreated between the carrier and the laser beam to provide a constantsupply of writing material. Relative motion is selectively createdbetween the workpiece and the laser beam to make new portions of theworkpiece surface available to receive material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a fabrication system capable of depositingmaterial onto a workpiece, the workpiece may have a flat surface asillustrated in FIG. 1, or a curved surface;

FIG. 2 is a cross sectional view of a substantially flat workpiece, alaser beam, and a carrier;

FIG. 3 is a plan view of a catheter having a strain relief and aradiopaque marker in accordance with the present invention;

FIG. 4 is a perspective view of an assembly including a generallytubular member having an outer surface, and a first electrode, a secondelectrode, a first conductor, and a second conductor disposed on theouter surface of the generally tubular member;

FIG. 5 is a fragmentary perspective view illustrating a method which maybe utilized to fabricate electrodes and conductors of any geometry;

FIG. 6 is a plan view an ablating burr having an abrasive layer inaccordance with the present invention;

FIG. 7 is a perspective view of a generally tubular workpiece having avisual marker disposed about its outer surface, a substantially flexiblecarrier including a layer of writing material, and a laser beam;

FIG. 8 is a perspective view of a generally tubular workpiece, asubstantially ring shaped carrier including a layer of writing material,and a laser beam;

FIG. 9 is a perspective view of a generally tubular workpiece, a carrierwhich may include a seam, and a laser beam;

FIG. 10 is a plan view of a generally tubular workpiece having aconductor or structural component disposed on its outer surface;

FIG. 11 is a plan view of a catheter in accordance with the presentinvention; and

FIG. 12 is a plan view of a catheter having a balloon in accordance withthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to thedrawings, in which like elements in different drawings are numberedidentically. The drawings which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope of theinvention.

Examples of constructions, materials, dimensions, and manufacturingprocesses are provided for selected elements. All other elements employthat which is known to those of skill in the field of the invention.Those skilled in the art will recognize that many of the examplesprovided have suitable alternatives which may be utilized.

FIG. 1 is a block diagram of a fabrication system 20 capable ofdepositing material onto a workpiece 22. In a presently preferredembodiment, workpiece 22 is a medical device having a generallycylindrical surface. Workpiece 22 is coupled to a workpiece motioncontrol system 24 which is capable of moving workpiece 22. Workpiecemotion control system 24 may include one or more linear actuators 26 andone or more rotary actuators 28.

A carrier 30 is positioned in close proximity to workpiece 22. Carrier30 is coupled to a carrier motion control system 32. Carrier motioncontrol system 32 may include one or more linear actuators and one ormore rotary actuators 28. In a presently preferred embodiment, carrier30 comprises a substantially laser transparent substrate 34. A layer ofwriting material overlays at least a portion of one surface of thesubstantially laser transparent substrate.

System 20 further includes a laser source 40 which is capable ofdirecting a laser beam 44. Laser source 40 is coupled to a laser controlsystem 42. In a presently preferred embodiment, laser source 40 isstationary. Embodiments are possible in which laser control system 42includes a plurality of linear actuators and a plurality of rotaryactuators. The actuators of laser control system 42 may be used toposition laser source 40 so that laser beam 44 illuminates a portion ofcarrier 30. Laser control system 42 may also be utilized to adjust thefocus of laser beam 44, by adjusting the distance between laser source40 and carrier 30.

As shown in FIG. 1, laser source 40 is also coupled to system controller50. System controller 50 may be used to selectively illuminate a portionof carrier 30 with laser beam 44. A number of methods and devices may beused to accomplish the selective illuminate of carrier 30, includingelectrical switches and mirrors. System controller 50 may also beutilized to selectively activate laser motion control system 42, carriermotion control system 32, and workpiece motion control system 24. Asshown in FIG. 1, system controller 50 is coupled to each of theseelements.

As described previously, workpiece motion control system 24, carriermotion control system 32, and laser motion control system 42 may allinclude one or more linear actuators. Those of skill in the art willappreciate that many embodiments of a linear actuator are possiblewithout deviating from the spirit and scope of the present invention.Linear actuators which may be suitable in some applications arecommercially available from Aerotech of Pittsburgh, Pa. and Anorad ofHauppauge, N.Y.

As described previously, workpiece motion control system 24, carriermotion control system 32, and laser motion control system 42 may allinclude one or more rotary actuators. Those of skill in the art willappreciate that many embodiments of a rotary actuator are possiblewithout deviating from the spirit and scope of the present invention.Rotary actuators which may be suitable in some applications arecommercially available from Aerotech of Pittsburgh, Pa. and Anorad ofHauppauge, N.Y.

FIG. 2 is a cross sectional view of a substantially flat workpiece 22, alaser beam 44, and a carrier 30. Carrier 30 comprises a substrate 34 anda layer of writing material 36 overlying one surface of substrate 34. Inthe embodiment of FIG. 2, writing material 36 includes a sacrificialportion 37 and a projectile layer 38.

As shown in FIG. 2, writing material 36 of carrier 30 is positioned inclose proximity to a surface 52 of workpiece 22. Laser beam 44 isadapted to illuminate a portion of carrier 30. In a method in accordancewith the present invention, laser beam 44 heats sacrificial layer 37causing it to be vaporized. The vaporization of sacrificial layer 37drives a projectile portion 39 of projectile layer 38 toward a surface52 of workpiece 22 at high speed causing projectile portion 39 to bondto workpiece 22.

In a presently preferred embodiment, substrate 34 is comprised of amaterial which is substantially transparent to laser beam 44. Suitablematerials for substrate 34 include polymeric and non-polymericmaterials. Examples of polymeric materials which may be suitable in someapplications include polyethylene (PE), polypropylene (PP), polyvinylacetate (PVA), polystyrene (PS), polyethylene terephthalate (PET),polybutylene terephthalate (PBT), and polytetrafluoroethylene (PTFE).Examples of non-polymeric materials which may be suitable in someapplications include glass, quartz, and sapphire.

In a presently preferred embodiment, sacrificial layer 37 is comprisedof a material which is effective at absorbing laser energy. Materialswhich may be suitable in some applications include carbon, polysulfone,and polyimide. In a presently preferred method, sacrificial layer 37does not decompose at high temperature and does not chemically interactwith the material of projectile layer 38. However, embodiments of thepresent method have been envisioned in which sacrificial layer 37 andprojectile layer 38 do interact chemically. For example, in one methodin accordance with the present invention, a layer of nickel and a layerof titanium are utilized and the material which is deposited on the workpiece is a nickel titanium alloy. Projectile layer 38 may be anymaterial which comprises a desirable addition to workpiece 22. Examplesof elements which may be fabricated using the process illustrated inFIG. 2 will be illustrated in the figures which follow.

FIG. 3 is a plan view of a catheter 54. Catheter 54 includes an elongateshaft 56 having a distal portion 58 and a proximal portion 60. Elongateshaft 56 is comprised of a distal tubular member 62, a proximal tubularmember 66, and a middle tubular member 64. A hub 70 is fixed to theproximal end of proximal tubular member 66. A strain relief 68 isdisposed about an outer surface 52 of proximal tubular member 66. Hub 70and strain relief 68 enable a physician to connect other devices tocatheter 54. Hub 70 and strain relief 68 also provide a convenient placefor a physician to apply longitudinal or rotational forces in order tomanipulate catheter 54. Strain relief 68 provides structural support toproximal tubular member 66 to make kinking less likely when these forcesare applied to hub 70. Strain relief 68 may be formed by applyingmaterial to outer surface 52 of proximal tubular member 66 using amethod in accordance with the present invention. Those of skill in theart will appreciate that strain relief 68 may be any shape or sizewithout deviating from the spirit and scope of the present invention.For example, embodiments of strain relief 68 have been envisioned inwhich strain relief 68 tapers from a generally wider diameter to agenerally more narrow diameter. Strain relief 68 may be any materialwhich provides the desired structural support. Examples of materialswhich may be suitable in some applications include polyethylene (PE),polypropylene (PP), polyvinylchloride (PVC), polyurethane,polytetrafluoroethylene (PTFE), polyether block amide (PEBA), stainlesssteel, nickel, titanium alloy and aluminum.

A radiopaque marker 72 is disposed about an outer surface 52 of distaltubular member 62. During a surgical procedure radiopaque marker 72assists a physician in determining the location of the distal tip ofcatheter 54 relative to a patients anatomy. Radiopaque marker 72 appearsas a relatively bright image on a fluoroscopy screen, allowing thephysician to “see” where the tip of the catheter is located. Radiopaquemarker 72 may be any material which provides the desired level ofradiopacity. Examples of materials which may be suitable in someapplications include gold, platinum, tungsten, iron, silver, andthermoplastic material loaded with a radiopaque filler. Examples ofradiopaque filler which may be suitable in some applications includebarium sulfate, bismuth subcarbonate, bismuth trioxide, bismuthoxychloride, bismuth subcarbonate, tungsten, and depleted uranium.Radiopaque marker 72 may be formed by applying material to the outersurface of distal tubular member 62 using a method in accordance withthe present invention.

FIG. 4 is a perspective view of an assembly 74 including a workpiece 22having a surface 52. Workpiece 22 may form a portion of a catheter. Afirst electrode 76 is disposed about outer surface 52 of workpiece 22.First electrode 76 is coupled to a first conductor 78. A secondelectrode 80 is also disposed about outer surface 52 of workpiece 22.Second electrode 80 includes a gap 84 which is adapted to allow firstconductor 78 to pass without making electrical conduct. Second electrode80 is coupled to a second conductor 82.

First electrode 76, second electrode 80, first conductor 78, and secondconductor 82 may all be comprised of any material which provides thedesired level of electrical conductivity. Examples of materials whichmay be suitable in some applications include gold, silver, and platinum.First electrode 76 and second electrode 80 may be used in conjunctionwith a number of medical procedures. Examples of such procedures includecardiac pacing, electrocardiograph recording, and percutaneousmyocardial revascularization (PMR).

Those of skill in the art will appreciate that other embodiments ofassembly 74 are possible without deviating from the spirit and scope ofthe present invention. For example, first conductor 78 and secondconductor 82 may form an electrical connection with elements other thanelectrodes. Examples of elements which may be coupled to first conductor78 and second conductor 82 include pressure sensors, temperaturesensors, flow sensors, and electromagnets.

FIG. 5 is a fragmentary perspective view illustrating a method which maybe utilized to fabricate first electrode 76, second electrode 80, firstconductor 78, and second conductor 82 of FIG. 4. In FIG. 5 a carrier 30is located proximate workpiece 22. As in FIG. 4, carrier 30 includes asubstrate 34 having a writing material 36 overlaying at least a portionof one surface. In a method in accordance with the present invention,workpiece 22 is coupled to a workpiece motion control system (not shownin FIG. 5). In the embodiment of FIG. 5, the workpiece motion controlsystem includes a rotary actuator (not shown). The rotary actuator isadapted to rotate workpiece 22 about an axis of rotation A. In apresently preferred method, axis A overlays the longitudinal axis ofworkpiece 22. Also in the embodiment of FIG. 5, the workpiece motioncontrol system includes a linear actuator (not shown). The linearactuator is adapted to move workpiece 22 longitudinally along axis A. Alaser source (not shown) is utilized to generate a laser beam 44.

Carrier 30 is positioned between the laser source and workpiece 22. Asshown in FIG. 5, carrier 30 is in close proximity of outer surface 52 ofworkpiece 22. In a presently preferred embodiment, carrier 30 comprisesa substantially laser transparent substrate 34, and a writing material36 overlaying the substantially laser transparent substrate 34. In theembodiment of FIG. 5, writing material 36 overlays the side of substrate34 which adjoins outer surface 52 of workpiece 22. In the embodiment ofFIG. 5, carrier 30 is coupled to a carrier motion control system. Thecarrier motion control system includes a first linear actuator which iscapable of moving carrier 30 along an axis C. The carrier motion controlsystem also includes a second linear actuator (not shown) which iscapable of moving carrier 30 along an axis D.

As shown in FIG. 5, first electrode 76, second electrode 80, firstconductor 78, and second conductor 82 have all been formed byselectively depositing material from writing material 36 onto outersurface 52 of workpiece 22. A method of applying material in accordancewith the present invention may be described with reference to FIG. 5.The process may begin with the step of coupling workpiece 22 to aworkpiece motion system. Carrier 30 may likewise be coupled to a carriermotion control system. Carrier 30 may be positioned so that it is inclose proximity to outer surface 52 of workpiece 22. A laser motioncontrol system may be used to position the laser source such that laserbeam 44 illuminates a portion of carrier 30 interposed between the lasersource and workpiece 22.

A system controller may be utilized to selectively activate the lasersource, laser motion control system, carrier motion control system, andworkpiece motion control system. Carrier 30 is selectively movedrelative to the laser beam to provide a constant supply of writingmaterial 36. First electrode 76 and second electrode 80 may be formed byrotating workpiece 22 while laser beam 44 illuminates a portion ofcarrier 30. The laser source may be moved as required to apply writingmaterial 36 to new portions of outer surface 52 of workpiece 22. Therotation of generally tubular member may be stopped and started asrequired to create the pattern of writing material 36 shown in FIGS. 4and 5. Likewise, laser beam 44 may be selectively applied to create thedesired pattern. It should be understood that steps may be omitted fromthis process and the order of the steps may be changed without deviatingfrom the spirit or scope of the invention.

As described previously, the workpiece motion control system, carriermotion control system, and laser motion control system may all includeone or more linear actuators and one or more rotary actuators. It shouldbe understood that the workpiece motion control system, carrier motioncontrol system, and laser motion control system may include any numberof linear actuators and any number of rotary actuators without deviatingfrom the spirit and scope of the present invention.

FIG. 6 is a plan view illustrating an additional method in accordancewith the present invention. An ablating burr 86 is illustrated in FIG.6. In a presently preferred embodiment, ablating burr 86 is adapted foruse in an atherectomy procedure. Ablating burr 86 includes a body member88 which is fixed to the distal end of a shaft 90. As shown in FIG. 6,the shape of body member 88 may generally be described as an ellipsoidalrotation.

In FIG. 6, a carrier 30 is located proximate a surface 52 of body member88. As in the previous embodiments, carrier 30 includes a substrate 34having a writing material 36 overlaying at least a portion of onesurface. In a method in accordance with the present invention, ablatingburr 86 is coupled to a workpiece motion control system (not shown inFIG. 6). In the embodiment of FIG. 6, the workpiece motion controlsystem includes a plurality of actuators. The workpiece motion controlsystem is adapted to rotate workpiece 22 about an axis of rotation E. Ina presently preferred method, axis E overlays the longitudinal axis ofablating burr 86.

A laser source (not shown) is utilized to generate a laser beam 44. Thelaser source is coupled to a laser motion control system (not shown). Inthe embodiment of FIG. 6, the laser motion control system includes aplurality of actuators which are capable of moving the laser sourcealong a path F. As shown in FIG. 6, path F generally follows the shapeof surface 52 of ablating burr 86.

Carrier 30 is positioned between the laser source and the ablating burr86. As shown in FIG. 6, carrier 30 is in close proximity of surface 52of ablating burr 86. In a presently preferred embodiment, carrier 30comprises a substantially laser transparent substrate 34, and a writingmaterial 36 overlaying the substantially laser transparent substrate. Inthe embodiment of FIG. 6, writing material 36 overlays the side ofsubstrate 34 which adjoins surface 52 of ablating burr 86. In theembodiment of FIG. 6, carrier 30 is coupled to a carrier motion controlsystem (not shown). The Carrier motion control system includes aplurality of actuators which are adapted to move carrier 30 along a pathG. Path G generally follows the shape of surface 52 of ablating burr 86.As shown in FIG. 6, an abrasive layer 92 has been selectively depositedon surface 52 of ablating burr 86.

A method of fabricating an ablating burr may be described with referenceto FIG. 6. The process may begin with the step of coupling ablating burr86 to a workpiece motion system. Carrier 30 may likewise be coupled to acarrier motion control system. Carrier 30 may be positioned so that itis in close proximity to surface 52 of ablating burr 86. A laser motioncontrol system may be used to position a laser source such that laserbeam 44 illuminates a portion of carrier 30 interposed between the lasersource and the ablating burr 86.

System controller (not shown) may be utilized to selectively activatethe laser source, laser motion control, carrier motion control system,and workpiece motion control system. Carrier 30 is selectively movedrelative to the laser beam to provide a constant supply of writingmaterial 36. In the embodiment of FIG. 6, writing material 36 includesabrasive particles 94.

FIG. 7 is a perspective view of a workpiece 22 having a visual marker 96disposed about its outer surface 52. Visual marker 96 is formed frommaterial which has been remove from a carrier 30 and deposited on outersurface 52. In the embodiment of FIG. 7, carrier 30 comprises anelongate, substantially flexible substrate 34. As in the previousembodiments, a writing material 36 overlays one surface of substrate 34.

In FIG. 7, a first portion of carrier 30 is disposed about a payoff reel100 and a second portion of carrier 30 is disposed about a take up reel102. Payoff reel 100 and take up reel 102 are each coupled to rotaryactuators (not shown). The reels 100, 102 are rotated such that carrier30 is fed off of payoff reel 100 and wrapped around take up reel 102.Between payoff reel 100 and take up reel 102, each portion of carrier 30passes in close proximity to a workpiece 22.

A laser beam 44 is positioned so that it illuminates a portion ofcarrier 30 proximate workpiece 22. Laser beam 44 may be selectivelyactivated to apply writing material 36 to workpiece 22. Carrier 30 iswound from payoff reel 100 to take up reel 102 such that it provides aconstant supply of writing material 36. Workpiece 22 is coupled to aworkpiece motion system which moves workpiece 22 to make new portions ofits surface available for deposition of writing material 36. The rotaryactuators, linear actuators, laser beam 44, laser control system, andworkpiece motion control system may all be selectively activated to formvisual marker 96.

FIG. 8 is a perspective illustrating an additional method in accordancewith the present invention. The method of FIG. 8 utilizes a carrier 30.Carrier 30 includes a generally tubular substrate 34 having an innersurface 104 defining a lumen 106. A writing material 36 overlays innersurface 104 of substrate 34.

As in the previous embodiments, generally tubular workpiece 22 iscoupled to a workpiece motion control. In the present embodiment,workpiece motion control is adapted to rotate generally tubularworkpiece 22 about an axis K. Carrier 30 is coupled to a carrier motioncontrol which is adapted to rotate carrier 30 about an axis L. Workpiecemotion control and carrier motion control may also be adapted to moveworkpiece 22 and carrier 30 longitudinally along axis K and axis L,respectively.

A laser beam 44 is positioned so that it illuminates a portion ofcarrier 30 proximate workpiece 22. When the laser source is activated,carrier 30 may be rotated to provide a constant supply of writingmaterial 36. Workpiece 22 may also be rotated to make new portions ofits lo surface available for deposition of writing material 36. Themethod illustrated in FIG. 8 may be utilized to form a variety ofelements by depositing writing material 36 onto outer surface 52 ofworkpiece 22. Elements formed with this process may be functional orpurely ornamental.

FIG. 9 is a perspective view illustrating an additional method inaccordance with the present invention. The present method utilizes acarrier 30 including a generally tubular substrate 34 having an innersurface (not shown) defining a lumen 106. In FIG. 9, a generally tubularworkpiece 22 is disposed within lumen 106 of carrier 30. As shown inFIG. 9, the outer diameter of generally tubular workpiece 22 issubstantially equal to the diameter of lumen 106. A writing materialoverlays the inner surface of substrate 34. In a presently preferredembodiment, there is a slight friction fit between carrier 30 andgenerally tubular workpiece 22 such that the writing material is inintimate contact with outer surface 52 of generally tubular workpiece22.

As in the previous embodiments, generally tubular workpiece 22 iscoupled to a workpiece motion control. In the present embodiment, theworkpiece motion control is adapted to rotate generally tubularworkpiece 22 about an axis M. In a presently preferred embodiment, axisM overlays the longitudinal axis of generally tubular workpiece 22.Because there is a friction fit between generally tubular workpiece 22and carrier 30, carrier 30 will rotate with generally tubular workpiece22. The workpiece motion control may also be adapted to move workpiece22 and carrier 30 longitudinally along axis M. A portion of the writingmaterial may be deposited onto outer surface 52 of generally tubularworkpiece 22 by selectively illuminating a portion of carrier 30 with alaser beam.

FIG. 10 is a plan view of a generally tubular workpiece 22 having aconductor 108 disposed on an outer surface 52. In the embodiment of FIG.10, generally tubular workpiece 22 may be comprised of a substantiallyflexible material. The generally helical path of conductor 108 makes itless likely that conductor 108 will crack when generally tubularworkpiece 22 is flexed. Conductor 108 may be used to provide anelectrical connection with a variety of elements. Examples of elementswhich may be coupled to conductor 108 include electrodes, pressuresensors, temperature sensors, flow sensors, and electromagnets.

Embodiments of conductor 108 have also been envisioned in whichconductor 108 performs a desired function. Examples of functionalconductors include antenna's and EMI shielding. Conductor 108 may befabricated using a method in accordance with the present invention.Those of skill in the art will appreciate that more than one conductormay be deposited on a workpiece without deviating from the spirit andscope of the present invention. For example, two conductors may bedeposited in the shape of a double helix. A portion of conductor 108 maybe covered with a layer of insulating material. This insulating materialmay be fabricated using a method in accordance with the presentinvention.

FIG. 11 is a plan view of a catheter 200 in accordance with the presentinvention. Catheter 200 includes a body 202 having an outer surface 204.A deposition 206 is disposed on outer surface 204 of body 202. In theembodiment of FIG. 11, deposition 206 has a generally helical shape witha variable longitudinal pitch. The pitch, and other factors, ofdeposition 206 may be varied to provide body 202 of catheter 200 with astiffness which varies longitudinally along body 202.

Embodiments of catheter 200 have been envisioned in which body 202 ofcatheter 200 comprises a plurality of tubular members. When this is thecase, deposition 206 could be placed at a transition point between twotubular members with different flexibility's to form a controlled strainrelief based the thickness and orientation of deposition 206.Embodiments of catheter 200 have also been envisioned in whichdeposition 206 creates a device which is more flexible in one planeverses another plane.

FIG. 12 is a plan view of a catheter 300 including a balloon 302 havingan outer surface 304. A deposition 306 is disposed on outer surface 304of balloon 302. In the embodiment of FIG. 12, deposition 306 includes aplurality of rings 308. It is anticipated that the presence of rings 308may reduce or eliminate the water- melon effect when inflating balloon302 in a lesion.

Embodiments of catheter 300 have been envisioned in which deposition 306comprises a spiral. Embodiments of catheter 300 have also beenenvisioned in which deposition 306 comprises a plurality of longitudinalstays. In these embodiments, it as anticipated that balloon 302 may forma plurality of lobes disposed between the stays when balloon 302 isinflated. It is also envisioned that the ends of the stays could beanchored proximate the ends of balloon 302.

Having thus described the preferred embodiments of the presentinvention, those of skill in the art will readily appreciate that yetother embodiments may be made and used within the scope of the claimshereto attached. Numerous advantages of the invention covered by thisdocument have been set forth in the foregoing description. It will beunderstood, however, that this disclosure is, in many respects, onlyillustrative. Changes may be made in details, particularly in matters ofshape, size, and arrangement of parts without exceeding the scope of theinvention. The inventions's scope is, of course, defined in the languagein which the appended claims are expressed.

What is claimed is:
 1. An apparatus for applying a layer of writingmaterial to a workpiece, said workpiece having an outer surface and alongitudinal axis, comprising a laser beam source capable of producing alaser beam; a carrier comprising a substrate, and a layer of writingmaterial overlaying the substrate; a carrier motion actuator capable ofmoving the carrier relative to the laser beam; a workpiece motionactuator capable of moving the workpiece rotationally about itslongitudinal axis relative the laser beam; a controller coupled to thecarrier motion actuator, the workpiece motion actuator, and the laserbeam source; the carrier being interposed between the laser source andthe workpiece; and the laser beam being adapted to illuminate a portionof the carrier.
 2. A method of forming a layer of writing material on asurface of a workpiece, the method comprising the steps of: providing alaser beam source capable of creating a laser beam; providing a carriercomprising a substrate, and a layer of writing material overlaying thesubstrate; coupling the carrier to a carrier motion actuator; couplingthe workpiece to a workpiece motion actuator; positioning the carrierbetween the laser beam source and the workpiece; illuminating a portionof the carrier with the laser beam; moving the carrier relative to thelaser beam; and moving the workpiece relative to the laser beam; whereinthe step of illuminating the portion of the carrier with the laser beamtransfers a portion of the writing material to the workpiece; whereinthe step of moving the workpiece relative to the laser beam includes thestep of rotating the workpiece about a first axis, said first axis beingthe longitudinal axis of the workpiece.
 3. The method of claim 2,wherein the step of moving the workpiece relative to the laser beamfurther includes the step of moving the workpiece in a direction alongits longitudinal axis.
 4. The method of claim 2, wherein the step ofmoving the carrier relative to the laser beam includes the step ofmoving the carrier in a first generally linear direction.
 5. The methodof claim 2, wherein the step of moving the carrier relative to the laserbeam includes the steps of moving the carrier in a first generallylinear direction and moving the carrier in a second generally lineardirection.
 6. The method of claim 2, wherein the step of moving thecarrier relative to the laser beam includes the steps of moving thecarrier in a first generally linear direction and moving the carrier ina second generally linear direction, the second direction being about 90degrees from the first direction.
 7. A method of forming a layer ofwriting material on a surface of a workpiece, the method comprising thesteps of: providing a laser beam source capable of creating a laserbeam; providing a carrier comprising a substantially laser transparentsubstrate, and a layer of writing material overlaying the substantiallylaser transparent substrate; coupling the carrier to a carrier motionactuator; coupling the workpiece to a workpiece motion actuator;positioning the carrier between the laser beam source and the workpiece;illuminating a portion of the carrier with the laser beam; moving thecarrier relative to the laser beam; and moving the workpiece relative tothe laser beam; wherein the step of illuminating the portion of thecarrier with the laser beam transfers a portion of the writing materialto the workpiece; wherein the step of moving the carrier relative to thelaser beam includes the step of rotating the carrier about a first axissuch that the carrier rotates about the workpiece.
 8. The method ofclaim 7, wherein the step of moving the carrier relative to the laserbeam includes the step of rotating the carrier about a second axis ofrotation.
 9. The method of claim 7, wherein the step of moving theworkpiece relative to the laser beam further includes the step of movingthe workpiece in a direction along its longitudinal axis.